Nope, I don't think so.... Here's a Q/A from Canon's site for the Canon 1DIII (note: not the 1Ds3, but I assume the sample principle applies)
I have a serious issue where the buffer fills up after a short burst and I have to wait and typically watch the best moments pass by. If I went from my current 5 MB/sec. card to a faster card, would that give me a much longer burst range? How fast does a card have to be in order to stay ahead of the camera's buffer if this is possible at all? By the way, I am shooting RAW to both CF and SDHC for full redundant backup.
Canons Answer wrote:
=Canon's Answer]The camera's buffer memory is used before the image data is written to a memory card, so the card's speed is not the only issue here. At best with the 1D Mark III, your burst rate is going to be approximately 33 to 36 RAW images or 110 to 120 consecutive Large JPEGs at 10 fps, even with the fastest memory cards available. (Incidentally, you get the same number of shots in a burst whether you record to one card or two cards simultaneously.) The number of shots will vary according to other settings. For example, you'll get fewer frames if you are shooting higher ISOs, RAW + JPEG, etc. One of the biggest buffer "killers" is setting the custom function for in-camera high ISO speed noise reduction. If you want to maximize the 1D Mark III's burst rate, shut that one off and do your noise reduction in post-processing.
How are you liking the 1Ds3? I don't like the time it takes to preview a photo after taking it (compared to the 5DII).
BTW. I gripped one of my 5DII, and you're right... a gripped 5DII is more monstrous than a 1Ds3. Although I do prefer the ergonomics of the 1Ds3 better.